Air filter containing filter bags

ABSTRACT

THE TOP AND BOTTOM AND SIDES OF AN UPRIGHT RECTANGULAR OUTER FRAME ARE PROVIDED WITH LONGITUDINAL CHANNELS OPENING TOWARD THE INSIDE OF THE FRAME. GLUED INTO THESE CHANNELS IN A GASKET. FILTER BAGS BEHIND THE FRAME HAVE OPEN ENDS DISPOSED SIDE BY SIDE INSIDE THE FRAME. THE TOP AND BOTTOM PORTIONS OF THE GASKET ARE GLUED TO THE ADJOINING ENDS OF THE BAGS. A NARROW RECTANGULAR INNER FRAME IS INSERTED IN THE OPEN END OF EACH BAG WITH ITS TOP AND BOTTOM HELD IN THE TOP AND BOTTOM CHANNELS. A U-SHAPED CLAMPING STRIP IS DISPOSED IN EACH SIDE CHANNEL AND STRADDLES THE OUTER SIDES OF THE ADJOINING BAG AND INNER FRAME TO CLAMP THEM TOGETHER. THE OUTER SIDE OF EACH CLAMPING STRIP IS GLUED TO THE ADJOINING SIDE PORTION OF THE GASKET.

NOV. 2, 1971 CQTABISH ETAL I 3,616,625

AIR FILTER CONTAINING FILTER BAGS Fil ed March 4, 1970 2 Sheets-Sheet l /4 I I INVI'ZNTORS.

HARRY xv. coma/5H FRANK H4 5114/ 771 ./-/2 BY WAY/V5 1.. 5M/7'H ATTORNEYS.

Nov. 2, 1 971 H. N. coTA alsl-i ETAI- AIR FILTER CONTAINING FILTER BAGS 2 Sheets-Shoot I Filed March 4, 1970 INVENTORS. HARRY N. COMB/5H FRANK (SM/Th BY MY/VE LSM/Tf/ fiwm,c/I6w .622%m United States Patent Office 3,616,625 Patented Nov. 2,, 1971 3,616,625 AIR FILTER CONTAINING FILTER BAGS Harry N. Cotabish, Allison Park, Frank W. Smith, Fox

Chapel, and Wayne L. Smith, Bradford Woods, Pa.,

assignors to Mine Safety Appliances Company, Pittsburgh, Pa.

Filed Mar. 4, 1970, Ser. No. 16,481 Int. Cl. B01d 46/02 US. Cl. 55483 3 Claims ABSTRACT OF THE DISCLOSURE The top and bottom and sides of an upright rectangular outer frame are provided with longitudinal channels opening toward the inside of the frame. Glued into these channels is a gasket. Filter bags behind the frame have open ends disposed side by side inside the frame. The top and bottom portions of the gasket are glued to the adjoining ends of the bags. A narrow rectangular inner frame is inserted in the open end of each bag with its top and bottom held in the top and bottom channels. A U-shape clamping strip is disposed in each side channel and straddles the outer sides of the adjoining bag and inner frame to clamp them together. The outer side of each clamping strip is glued to the adjoining side portion of the gasket.

In Pat. 3,190,059 a filter is shown of the general type disclosed herein. In that filter the outer sides of the two outermost frames inserted in the open ends of the filter bags have to be riveted to the adjoining sides of the outer rectangular frame to form a seal and keep them from buckling. Also, the top and bottom of each narrow inner frame must be riveted to the top and bottom of the surrounding outer frame to hold them in place.

It is among the objects of this invention to provide an improved air filter which requires a minimum of rivets, and which has a good seal around the open ends of the bags.

The invention is illustrated in the accompanying drawings, in which FIG. 1 is a fragmentary perspective view of the front end of the filter;

FIG. 2 is an enlarged fragmentary front view of the filter, partly broken away in section;

FIG. 3 is a horizontal section taken on the line III-III of FIG. 2;

FIG. 4 is a vertical section taken on the line IV-IV of FIG. 2; and

FIG. 5 is a fragmentary front view of a modification, partly broken away in section.

Referring to FIGS. 1 to 4 of the drawings, the rectangular outer frame 1 will be considered herein as being in an upright position for ease of description, but it will be understood that it could be in any other position without altering the invention claimed herein. The frame, as shown in FIGS. 3 and 4, has an outer wall 2 from which parallel front and back walls 3 and 4 extend inwardly. The inner marginal portions of the front and back walls are folded inwardly upon themselves and then turned inwardly toward each other to form flanges 5. The result is that the top and bottom of the frame and the sides that connect the top and bottom are provided with longitudinal channels that open toward the inside of the frame. Since the ends of these channels join one another, a continuous channel is formed around the inside of the frame. A gasket 6 is disposed in the channel and is secured to its inner wall, formed by flanges 5, by means of a suitable adhesive 7.

Behind the frame there are several filter bags 9 that are disposed side by side. These bags are much higher than they are wide and may be any desired length. They are open only at their front ends, which are disposed side by side inside the frame. Adhesive 10 secures the inner side of the top and bottom portions of the gasket to the adjoining ends of the bags as shown in FIGS. 2 and 4.

zInserted in the open end of each bag in tight engagement with it is a relatively narrow rectangular inner frame 12. In other words, the open end of each bag is stretched around one of these inner frames. The top and bottom of each inner frame is disposed within the top and bottom channels, respectively, of the outer frame 1 as indicated in FIGS. 2 and 4. The tops and bottoms of the inner frames therefore cannot be moved forward or backward out of the outer frame because they are held in the channels.

Another feature of this invention is that a long U-shape clamping strip 14 of sheet metal is at least partly disposed in each side channel of the outer frame, as shown in FIGS. 2 and 3. The clamping strip straddles the adjoining outer side of the bag and the outer side of the inner frame in that bag, whereby to clamp the bag and frame tightly together. The outer side of each clamping strip is secured to the side portion of the gasket beside it by means of an adhesive 15. The free edge of the outer side of the strip may be rolled over to eliminate any possibility of its cutting the bag.

The rest of the inner frames are connected side by side and to the two end frames in the row by means of rivets 17 or the like in order to compress the portions of the bags between them to form a good seal.

It will be seen that because of the gasket and its adhesion to the outer frame and to the bags or the clamping strips, the bags are securely sealed in the outer frame so that there is no danger of leakage around them. At the top and bottom of the filter the gasket seals any gaps that otherwise might be created by the longitudinal seams of the filter bags between the outer frame and the tops and bottoms of the inner frames. Also, if there is any lateral movement of the inner frames, the gasket can expand or contract to compensate for it without allowing leakage.

There is no requirement for rivets through the outer frame because its channels hold the inner frames in place. The two clamping strips 14 also make rivets in those locations unnecessary because the strips reinforce and stiffen the outer sides of the inner frames so that those sides will not bow or buckle away from the outer frame and therefore do not need fasteners to prevent it.

In the modification shown in FIG. 5, the inner rectangular frame 21 at each end of the row of frames has a central gap 22 in it. This gap is bridged by a U-shape clamping strip 23, the opposite ends of which straddle the outer side of the bag end and the outer side of the inner frame at the opposite ends of the gap. The central portion of the strip is clamped against both sides of the portion of the bag spanning the gap. Here again the outer side of the strip is fastened by adhesive 24 to a gasket 25 held by adhesive 26 in the channel of an outer rectangular frame 27.

We claim:

1. An air filter comprising an upright rectangular outer frame having front and back and top and bottom walls, the top and bottom walls and the frame sides connecting them being provided with longitudinal channels opening toward the inside of the frame, a gasket in said channels, adhesive securing the outer side of the gasket to the adjoining wall of each channel, a plurality of filter bags behind the frame having open front ends disposed side by side inside the frame, adhesive securing the inner side of the top and bottom portions of the gasket to the adjoining ends of the bags, a relatively narrow rectangular inner frame inserted in the open end of each bag in tight engagement therewith, the top and bottom walls of each inner frame being held in the top and bottom channels respectively, a U-shape clamping strip disposed in each side channel and straddling the outer sides of the adjoining bag and inner frame to clamp them together, adhesive securing the outer side of each clamping strip to the adjoining side portion of the gasket, and means connecting the remaining sides of the inner frames in pairs to compress the bag ends between them.

2. An air filter according to claim 1, in which said frame has an outer wall and parallel front and back walls extending inwardly from the outer wall, the inner marginal portions of the front and back walls being folded inwardly upon themselves and then turned inwardly toward each other to form said channels.

3. An air filter according to claim 1, in which said outer side of the inner frame at each end of the row of UNITED STATES PATENTS 3,190,059 6/1965 Bauder et a1. 55491 3,247,652 4/1966 Annas et a1. 55-483 3,400,519 9/1968 Korn et al. 55-484 FRANK W. LUTTER, Primary Examiner B. NOZICK, Assistant Examiner US. Cl. X.R. 

